about power system (real and reactive power)

what is mean by real power(P) and reactive power(Q).(please explain it . not in formula).Tell me in way of practically.

real power is the actual power which is supplied to the ckt in kW

the reactive power is the opposing power which is induced in the ckt due to the inductive components in the ckt

all ckts have inter twinned R,L,C components the real power is the power developed for a pure RESISTOR load

and reactive power is developed in any reactive load it may be a capacitor or inductor

thank you for your reply . k then how capacitor(synchronus condenser,tap changer..etc.) can compensate it.

Hi,
first of all in ac we have " 3 types of power " : apparent power [VA], active power [W] and reactive power [VAr].
Now to your questions (without formula :grin: ) : i belive a more intuitive explication is offered by treating the subject under energetical aspects:
- the active power [w] is the power that is produced ( power plant ) and consumed, converted in other forms of energy ( electric recivers ) .
- reactive power is produced in electro-energetic systems by elements which have inductive and capacitive characteristics and the difference is that this kind of electric power is not consumed and usefully transformed in other forms of energy by electric recivers , it is a transferred power (i call it ping-pong power :grin: ) which only over charges power lines (increses the current) That is why the need of compensation exists in such electroenergetical systems.
About compensation.
Reactive power can be of 2 types starting by the produceing element (condensator type or coil type ) : capacitive VAr and inductive VAr . If in a system VAr circulation is produced by coil type reactive elements then the compensation can be made by capacitive type of elements or by other elements that can perform a capacitive characteristic (for example the synchronous compensator can work in capacitive domains and inductive domains). In the same way capacive VAr can compensate inductive VAr.
Now how do i distinguish inductive VAr from capacitive VAr ?
It is simple : from phase shift of current and voltage. By inductors first the voltage passes thro zero (we are in AC) and then the current. By capacitors voltage passes thro zero after the current

- - - Updated - - -
**broken link removed**

some graphic (no formula)

Link to animated simulation showing how an inductive load creates reactive power factor, and briefly explaining how power is lost because of phase difference:

https://www.falstad.com/circuit/e-powerfactor1.html

Showing how power factor can be corrected using a capacitor (avoiding loss of power):

https://www.falstad.com/circuit/e-powerfactor2.html

k. i have understood what is real and reactive power. but again i have one doubt. here we are using capacitor for compensating power factor also(am i correct?). why we are compensate it. what are the problem if is less power factor.

if the power factor is less then the efficiency of the op to the ip is going to be very less and so we always use capacitor to boost the power factor

p=VI cos(angle)

cos (angle ) is the power factor

to increase we add a component to increase it

cap produces a leading op and so in case of a inductive supply only we use it to increase the power factor


if the supply is a capactitve one we go for an inductor to improve power factor by bringing the angle to nearly 0

visva said:

k. i have understood what is real and reactive power. but again i have one doubt. here we are using capacitor for compensating power factor also(am i correct?). why we are compensate it. what are the problem if is less power factor.

Click to expand...

When our power factor is less than one, the electric company (generator, etc.) must work harder to overcome our load's reactance.

The result is our electricity costs more one way or the other.

By adding compensation we reduce reactance to zero. We optimize our load's efficiency, thus we pay less to run it.

not only the cost but also the efficiency of the power produced depends on the reactance value

if the power factor is almost 1 we will get the maximum efficient op from the generator and the losses are quite minimal then only the cost is lower